With the development of digital broadcasting and the convergence of broadcasting and communication, the development of new services in such convergence fields has been in progress.
A conventional broadcasting transmits a variety of optimized parameters in a frequency band of an allocated radio wave. A broadcast transmission path is excellent in terms of a wide coverage area and a simultaneous distribution (simultaneousness and sameness). It is suitable for transmitting a small quantity of contents to a very large number of receivers at the same time, which are distributed geographically. However, since a specification for a target receiver is predefined and it is assumed that it will be operated over a long term, it is difficult to drastically modify various parameters or amend a fundamental method at a later time.
In a conventional communication, a variety of parameters are optimized in an allowable bandwidth of a communication path prior to transmission. A communication transmission path is excellent in terms of locality and individuality. It is suitable for a case where different contents are transmitted to explicit individual terminals. Thus, a specification for a target receiver can be individually considered, and it is relatively easy to drastically modify various parameters or amend a fundamental method at a later time. Further, although there is a method of realizing a wide coverage area and a simultaneous distribution in a communication, it is advantageous in terms of quality but is disadvantageous in terms of scale and simultaneousness when compared to broadcasting.
Additionally, H.264/SVC (Scalable Video Coding) has been proposed as a technique that can dynamically change a content transmission rate or select data streams of different parameters in accordance with another receiver specification when communication quality of a transmission path is degraded by a certain cause. H.264/SVC is a technique that can previously generate and output a plurality of data streams at the same time and obtain contents of a desired transmission rate solely through a combination thereof.
More specifically, a plurality of data streams include a base stream and a plurality of extension stream. A base stream is a data stream itself of a lowest rate whereas data streams. A plurality of data stream except for the base stream are data streams configured as extension streams corresponding to each difference from the base stream. These data streams are generated in an encoding device. Thus, a transmitting device, a receiving device or a decoding device can change a transmission rate by merely increasing or decreasing the selection of the number of extension streams transmitted by the transmitting device. It is possible to obtain contents matched with a receiver specification only if unnecessary extension streams are discarded.
However, in the conventional technique, it is assumed that the video data is transmitted or received simply using a single type of transmission path. Further, it is preferable that the data streams transmitted over the broadcasting transmission path are identical to the data streams transmitted in the existing broadcasting in accordance with the receiver specification for the existing broadcasting. Under these circumstances, it is very difficult to improve playback quality using different types of transmission paths.